Overview

An e4 application is completely backed up by a domain model often called Workbench or Application Model but in contrast to e.g. the browser DOM which only holds visual elements the e4 application model also holds other informations relevant to an e4 application (e.g. commands, handlers, ...). This makes the e4 application model the center of each e4 application.

From a technical point of view the e4 application model is defined using EMFs Ecore meta model. For an average user the usage of EMF in the background is completely transparent and you don't need to know about EMF to write an develop e4 applications (you won't even notice that you are using EMF because the API presented to you is not holding EMF-Types). For people who'd like to extend the workbench model a certain knowlegde about EMF is certainly needed.

UI Layer

As outlined before the application model holds the main UI structure of an e4 application. When we talk about the main UI structure this means everything part of the Application Window (Menus, PartStacks, ...) and e.g. Part menus but not the UI shown inside an application Part (e.g. the Tree in the PackageExplorer)

The following screenshot displays the domain model making up the ui on the left and the rendered application

One of the most important things when talking about the application model we need to know that ALL modification made in the model are immediately reflected in the UI. It is in contrast so that you are only programming against the application model and not against its visual representation. This now is indeed similar to how you are implementing Browser-Applications where also modify the DOM and the browser updates the visual representation.

The ui-domain objects are organized in 3 different packages:

menu: Holding menu and toolbar domain objects

basic: Basic UI domain objects e.g. to create windows, stacks, ...

advanced: Advanced UI domain objects e.g. to create perspectives

Basic UI Domain Objects

These domain objects are needed to write a simple to medium size e4 application providing you with the most common UI concepts like Window, Sash and Stack.

Windows

There are 2 domain types available to define a window in your application.

Window

Represents a standard window used by application who are not in need of advanced stuff.

Inheritance:

Attributes:

Class

Feature

Type

Description

MWindow

mainMenu

Menu

The main menu shown in the menubar of the Shell

x

int

The x position on the screen

width

int

The width of the window

height

int

The height of the window

windows

List<Window>

Child Windows

sharedElements

List<UIElement>

Shared Elements are quite an advanced concept coming into Eclipse through perspectives. Normally an UI-Tree is made up of only contaiments but without the idea of links. In an Eclipse Application this is not necessarily this way because e.g. the editor-area with all its editors is shared between different parts of the model (the perspectives), the same holds true for certain parts (e.g. the Package Explorer). The currently supported elements to share are MPart and MPartSashContainer

MBindings

bindingContexts

List<String>

Keybinding contexts active in this window

MContext

context

IEclipseContext

The IEclipseContext used by the DI-Framework for injection

variables

List<String>

Variables defined in this context (see IEclipseContext description)

MElementContainer

children

List<MWindowElement>

Child elements layouted in the windows content pane

selectedElement

MWindowElement

The currently active childcontrol

MUIElement

widget

Object

the real UI-Control (e.g. SWT-Widget) rendering the element

renderer

Object

The renderer resposible to create the UI-Control and sync it with the elements attribute

toBeRendered

boolean

onTop

boolean

visible

boolean

parent

MElementContainer<MUIElement>

The parent container

containerData

String

curSharedRef

MPlaceholder

visibleWhen

MExpression

MApplicationElement

elementId

String

id to identify the element e.g. when contributing

tags

List<String>

Arbitary strings used to tag elements so that one can query for them

MHandlerContainer

handlers

List<MHandler>

list of handlers

MUILabel

label

String

The label displayed on the window

iconURI

String

The icon displayed on the window

tooltip

String

TrimmedWindow

Represents a window with TrimBars e.g. to show a ToolBar at the top, a StatusBar at the bottom and minimized Stacks at the right and left

Containers

There are 2 default containers used by e4 applications to build the UI-Tree. The difference between them is that PartSashContainer is designed to show all of its children at once whereas PartStack is showing only one of its children at a time.